A remote controlled multimode micro-stimulator for freely moving animals.

This paper presents a remote controlled multimode micro-stimulator based on the chip nRF24E1, which consists mainly of a micro-control unit (MCU) and a radio frequency (RF) transceiver. This micro-stimulator is very compact (18 mmx28 mm two layer printed circuit board) and light (5 g without battery), and can be carried on the back of a small animal to generate electrical stimuli according to the commands sent from a PC 10 meters away. The performance and effectiveness of the micro-stimulator were validated by in vitro experiments on the sciatic nerve (SN) of the frog, where action potentials (APs) as well as artifacts were observed when the SN was stimulated by the micro-stimulator. It was also shown by in vivo behavioral experiments on operant conditioned reflexes in rats which can be trained to obey auditory instruction cues by turning right or left to receive electrical stimulation ('virtual' reward) of the medial forebrain bundle (MFB) in a maze. The correct response for the rats to obey the instructions increased by three times and reached 93.5% in an average of 5 d. This micro-stimulator can not only be used for training small animals to become an 'animal robot', but also provide a new platform for behavioral and neurophysiological experiments.